Missions to study asteroids
Close-up observations by spacecraft have provided most of our detailed knowledge about asteroids.
Past missions
Launch 17 February 1996: NEAR Shoemaker (Near Earth Asteroid Rendezvous)
A NASA Discovery mission, NEAR Shoemaker made a fly-by of the main-belt asteroid 253 Mathilde on 27 June 1997. It then became the first spacecraft to visit a near-Earth asteroid, 433 Eros, on 23 December 1998. Although an orbital insertion manoeuvre failed, NEAR Shoemaker was able to obtain over 1000 distant images of Eros. During a second attempt, NEAR Shoemaker successfully entered orbit around Eros on 14 February 2000 and began to map its surface at high resolution. On 12 February 2001, it became the first spacecraft to land on an asteroid. (NASA).
Launch 24 October 1998: Deep Space 1
A NASA New Millennium mission to try out innovative technology, particularly a solar electric propulsion unit and an autonomous navigation system. Deep Space 1 completed a fly-by of the asteroid 9969 Braille, on 28 July 1999. However, its images were limited to a few distant views when the spacecraft cameras failed to point towards the dark target. The spacecraft was retired on 18 December 2001. (NASA).
Current and future missions
Launch 18 October 1989: Galileo
On its way to Jupiter, as Galileo flew past the main-belt asteroid 951 Gaspra on 29 October 1991, it obtained the first high-resolution images of an asteroid. On 28 August 1993, the spacecraft had a close encounter with the main-belt asteroid 243 Ida. During this encounter, it discovered that Ida possesses a small moon, subsequently named Dactyl. Galileo is destined to plunge into Jupiter's atmosphere in September 2003. (NASA).
Launch 15 October 1997: Cassini-Huygens
On its way to Saturn, Cassini-Huygens crossed the main belt and took pictures of the asteroid 2685 Masursky on 23 January 2000. The images revealed that the side of Masursky imaged by Cassini is roughly 15-20 kilometres across. (NASA/ESA).
Muses-C
A Japanese mission scheduled for launch mid-2003, it will be the first asteroid sample return mission. The spacecraft will make a landing on the near-Earth asteroid 1998 SF36 in 2005 and return a soil sample to Earth in June 2007. (ISAS/NASA).
Rosetta
Scheduled for launch in 2003, Rosetta will encounter two main-belt asteroids, 140 Siwa and 4979 Otawara, in the years 2006 and 2008 on its way to Comet Wirtanen. (ESA).
Dawn
A NASA mission to rendezvous and orbit the asteroids 4 Vesta and 1 Ceres. Scheduled for launch in mid-2006, Dawn will reach Vesta in July 2010. After about one year orbiting the asteroid, it will depart for Ceres, arriving in August 2014. (NASA).